Centrifugal pumps

ABSTRACT

A centrifugal liquid pump of the kind wherein an auxiliary vacuum pump assists in priming and removing unwanted gas during subsequent operation, is provided with a primary chamber to contain liquid and to receive unwanted gas which has entered the pump, an upper port in said chamber for removal of gas by said vacuum pump, a float-operated valve device to control said port, a secondary chamber connected at its upper part to said port, and a valve-controlled return passageway extending from a lower part of the secondary chamber to said primary chamber. The secondary chamber has an upper opening to said vacuum source whereby gas from said primary chamber is extracted via the secondary chamber in which entrained liquid is deposited and, on opening said secondary chamber to atmosphere, the occurring pressure differential between the chambers discharges deposited liquid in the secondary chamber through said return passageway to the primary chamber. The float-operated valve device may be arranged to open said secondary chamber to atmosphere when the valve device operates to close said port, and a manually-operable valve may be provided to admit atmospheric air to said secondary chamber and effect discharge of the deposited liquid, independently of the floatoperated valve device.

United States Patent Paish et al.

Sept. 9, 1975 CENTRIFUGAL PUMPS Primary Emminer-Henry F. Raduazo [75] Inventors: Harold Philip Sidney Paish; Henry Smith, both of London, England [57] ABSTRACT A centrifugal liquid pump of the kind wherein an aux- [73] Asslgnee' Sykes Pumps Lmmed London iliary vacuum pump assists in priming and removing England unwanted gas during subsequent operation. is pro- [22] Filed: Mar. 6, 1974 vided with a primary chamber to contain liquid and to receive unwanted gas which has entered the pump, an [2 1] Appl' 448752 upper port in said chamber for removal of gas by said vacuum pump, a float-operated valve device to con- [30] Forei A li ati P i it D t trol said port, a secondary chamber connected at its Mar 6 [973 United Kingdom H [0923/73 upper part to said port, and a valve-controlled return passageway extending from a lower part of the sec- U S CL u ondary chamber [0 said primary Chamber. Th3 SCC- [51] Int. Cl. FiMD 9/00 Ondary Chamber has an upper Opening to said vacuum [58] Field of Search V H HS/53 I45 144; 4|7/l99 source whereby gas from said primary chamber is ex- 417ll99 A 200 20! 202 305 306 tracted via the secondary chamber in which entrained 1 liquid is deposited and, on opening said secondary [56] References Cited chamber to atmosphere, the occurring pressure differ- UNITED STATES PATENTS ential between the chambers discharges deposited liq uid in the secondary chamber through said return pas- 1 445507 2/1923 Hacntjcns 417/200 Sageway to the primary chamber 1390.317 lZ/l932 Durdin Jr... 4l7/200 1,910,775 5 1933 Saxc 417/200 The flow-Operated Valve may be arranged to 137 1 774 3 1934 di JrM 4 7 2 0 open said secondary chamber to atmosphere when the 2315946 8/1943 Durdin, Jrm. 4444 417/190 A valve device operates to close said port. and a 2. 41 2 /l 45 ch c l.. 417/200 manually-operable valve may be provided to admit 2535583 l2/l950 Kroll 417/200 atmospheric air to Said secnndary chamber and ff t FOREIGN PATENTS OR APPUCATIONS discharge of the deposited liquid. independently of the 503,310 4/1939 United Kingdom 417/200 floatopermed valve devlce 8 Claims, 3 Drawing Figures CENTRIFUGAL PUMPS BACKGROUND OF THE INVENTION This invention relates to centrifugal liquid pumps of the kind provided with auxiliary vacuum pumps or like vacuum sources which assist in printing the pumps and removing air during subsequent operation. Centrifugal pumps of this kind are marketed under our Trade Marks Velovac and Univac, and are described in the specifications of our British Pat. Nos. 755,249, 1,048,272 and 1,050,893.

With centrifugal pumps of the above kind it is important to prevent the water reaching the auxiliary vacuum pump, and this involves the provision of a cut-off valve which is usually operated by a float in a chamber. Valve arrangements of this type, such as described in the specification of our US. Pat. No. 3,726,303, are extremely useful but, unless the chamber is of a size which is so large as to be more or less impracticable, water tends to be carried through the cut-off valve to the vacuum pump. Also, known cut-off valve arrangements tend to be complex and expensive and, unless they are of cumbersome dimensions, the valves can constrict the suction passageway to the vacuum pump which may involve the provision of a more powerful vacuum pump than would otherwise be necessary.

It is an object of the present invention to provide a control valve arrangement in which the above disadvantages are at least reduced.

SUMMARY OF THE INVENTION According to the present invention there is provided a centrifugal liquid pump of the kind wherein an auxiliary vacuum pump or like vacuum source assists in priming and removing unwanted gas during subsequent operation, the centrifugal pump being provided with a primary chamber arranged to contain liquid and to receive unwanted gas which has entered the pump, an upper port in said chamber for removal of gas by said vacuum source, float-operated valve means to control said port, a secondary chamber connected at its upper part to said port, a valve-controlled return passageway extending from a lower part of the secondary chamber to said primary chamber, and said secondary chamber has an upper opening to said vacuum source whereby gas from said primary chamber is extracted via the secondary chamber in which entrained liquid is deposited and, on opening said secondary chamber to atmosphere, the occurring pressure differential between the chambers discharges deposited liquid in the secondary chamber through said return passageway to the pri mary chamber.

Preferably, said float-operated valve means are arranged to open said secondary chamber to atmosphere when said valve means operate to close said port.

Manually-operable valve means may also be provided to admit atmospheric air to said secondary chamber and effect discharge of the deposited liquid, independently of the floatoperatcd valve means.

Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation showing a centrifugal liquid pump;

FIG. 2 is an end view in the direction of arrow ll of FTG. l; and,

FIG. 3 is a fragmentary section, to an enlarged scale, showing the air separation chamber of the pump.

DESCRIPTTON OF PREFERRED EMBODlMENTS Referring to the drawings, the pump is of the kind described in our aforementioned Patent specifications and functions as a suction pump to deliver water, some times against a substantial head. A continuouslyrunning auxiliary vacuum pump (not shown) is provided for priming t remove air from the centrifugal pump and/or from the suction pipe and for removal of air which, during operation, enters the centrifugal pump through the suction pipe and/or by leakage into the pump casing.

The pump now illustrated comprises a primary chamber 10 at the lower part of which a volute casing 11 is arranged. The volute casing houses a rotary impeller 12 mounted at the end of a shaft 13 which extends through side wall 14 of the chamber 10 to be driven by a directcoupled motor (not shown). The shaft 13 drives a belt 15 which drives the auxiliary vacuum pump.

The upper part of the chamber 10 acts as a water reservoir and as a float chamber. The chamber 10 is also formed, at a lower part, with an inlet or suction opening 16 for inflow of water, and a port 17 is provided in top wall 18. The port 17 is controlled by a float-valve arrangement and is in communication with the vacuum pump, through an air-separation chamber 19, as will subsequently be described.

The volute casing 11 extends tangentially upwardly at 20 to open into an upper sub-chamber 21. A flap valve 22 is provided at the opening into the subchamber 21, and a delivery opening 23 for outflow of water is arranged at the top of the sub-chamber.

The pumping unit described above is self-priming. At the start of an operation the flap valve 22 is closed and the vacuum pump extracts air from the chamber 10 through the port 17, to draw water in through opening 16. The water rises within chamber 10 to enter the volute entries (not shown) around the level of the shaft 13, and be pumped by the rotating impeller 12 upwardly past the flap valve 22 and through the delivery opening 23.

As the operation of the pump proceeds, the chamber 10 is partly filled with water, and air which has entered the pump through the suction pipe passes to the space above the water level which is liable to fluctuate and surge. The present pump construction aims to prevent surging water from chamber 10 being carried through to the vacuum pump. To this end, the air-separation secondary chamber 19 is arranged alongside chamber 10, and an upper passageway 24 leads from the port 17 to the chamber 19. A valve arrangement 25 is mounted on the top cover 18 of the chamber 10, and is operated by means of a float 26 which is carried by an arm 27 pivotally mounted on a bracket 28 depending from the wall 18, and which is comparable to float 27 of British Pat. No. 1,048,272 or float 32 of British Pat. No. 1,050,893.

A return passageway 29 opens from the bottom of the chamber 19, and extends to an upper part of the primary chamber 10. A ball 30 near the lower end of the passageway 29 operates as a one-way valve to control liquid flow through the restricted outlet opening from the passageway. A glass or like transparent plate 3] is secured over an inspection opening 32 in the side wall of the chamber 19.

At the top of chamber 19 an opening 33 leads through orifices 34 to the auxiliary vacuum pump, and a manually-operated valve device 35 is provided for the purpose hereinafter described.

In normal operation of the pump, air is extracted from the primary chamber 10, and passes through port 17, passageway 24, chamber 19, opening 33, and orifices 34 to the constantly-running auxiliary vacuum pump. During this operation, a small quantity of water may, under certain circumstances when the water level in chamber surges upwardly, be carried into chamber 19. When the water level does surge up, the floatcontrolled valve arrangement 25 is operated to close port 17.

The valve arrangement 25 comprises a stem 36 which is connected to the float-carrying arm 27 and on which are secured lower and upper closure members 37 and 38. A disc 39 is a sliding fit on the stem which is urged upwardly by a helical compression spring 40. Thus, when the float 26 in chamber 10 lifts the valve stem 36, the member 38 is firstly raised to open the passageway 24 to atmosphere and the inrushing atmospheric air, assisted by a light compression spring 41, snaps the disc 39 down to close port 17 against entry of atmospheric air to the low-pressure chamber 10; thus, momentarily, a pressure differential is created between the chamber 19 into which atmospheric air has entered through passageway 24, and the chamber 10, and any water which has collected in chamber 19 or passageway 29 will be blown into chamber 10. The pressure differential is short-lived, but has proved to be very adequate for its purpose. When the water level i chamber 10 subsides, the valve arrangement will return to the position shown in the drawings, with the disc 39 held clear of port 17 by the air being extracted through the port by the auxiliary vacuum pump.

The manually-operable valve device 35 comprises a stem 42 to which a two-faced closure member 43 is secured, and the stem is urged upwardly by a helical compression spring 44 acting on a disc 45. The disc 45 is backed by a knob 46 which is screwed onto the threaded upper end of the stem. The valve device 36 which. it is envisaged, may be employed without the valve arrangement 25 or with a simplified float-valve arrangement, performs the following functions:

i. Water which has gathered in the chamber 19 and the passageway 24 can be discharged in a manner similar to that described above, by depressing the knob 46 to admit atmospheric pressure to the chamber 19 and possibly isolate the vacuum pump. The momentary pressure differential which exists inbetween chambers 19 and 10 before atmospheric pressure can reach the latter is sufficient to discharge any collected water into the chamber 10; in this case, the knob is only briefly, and possibly lightly depressed.

ii. A more firm depression of the knob 46 will isolate the vacuum pump and expose chambers 19 and 10 to atmospheric pressure, and thus a blocked suction entry may be cleared by flushing back the water in the system. lt is to be noted that the spring 44, supplemented by an optional inner spring 47, should be sufficiently powerful to free the closure member 43 from orifice 34 to which a high degree of vacuum may be applied.

iii. Adjustment of the degree of compression of spring 44 can cause the valve device 35 to open at any desired degree ofvacuum and so control the pump output and match the liquid flow to the pump suction.

iv. A gauge can be inserted at orifice 48 and the knob 46 depressed fully to isolate the auxiliary vacuum pump for testing.

lt will be appreciated that the valve arrangement 25 operates automatically without requiring the attention of an operator. On the other hand, the provision of the valve device 35 allows an operator to clear the chamber 19 if he notices through the inspection opening 32 that water is collecting and also, of course, allows him to perform the other three functions mentioned above. As a further protection against water being carried to the auxiliary vacuum pump, a float valve or ball valve indicated at 49 in FlG. 3 may be provided to control opening 33.

We claim:

1. A centrifugal liquid pump of the type wherein an auxiliary vacuum source assists in priming and removing unwanted gas during operation thereof, the centrifugal pump comprising a primary chamber which contains liquid and receives unwanted gas which has entered the pump; an upper port in said primary chamber in communication with said vacuum source for removal of gas from said primary chamber; float-operated valve means which control said upper port; means defining a secondary chamber having upper and lower parts, said upper part being disposed between and in communication with said port and said vacuum source; a return passageway extending from said lower part of the secondary chamber to said primary chamber; second valve means in said return passageway operable to permit liquid flow from said secondary chamber to said primary chamber when the pressure in said secondary chamber is greater than that in said primary chamber; said secondary chamber having an upper opening in communication with said vacuum source and through which gas from said primary chamber is extracted via said port and the secondary chamber; said float-operated valve means being operable to open said secondary chamber to atmosphere when said port is closed by said floatoperated valve means in response to a predetermined rise in the liquid level in said primary chamber; whereby entrained liquid deposited in said secondary chamber is discharged to said primary chamber through said return passageway as a result of the pressure differential which occurs between the primary and secondary chambers when said secondary chamber is opened to atmosphere.

2. A centrifugal pump as claimed in claim 1, in which said float-operated valve means comprise an upright stem which extends through said port and is raised and lowered by said float; a lower closure member secured to said stem to seat on said port when the stem is in a raised position; an upper closure member which is secured to said stem and which controls an opening in the pump housing which connects said secondary chamber to atmosphere; an intermediate valve member which slides on said stem and which closes said port when in a lower position; whereby when the stem with the upper closure member is raised by the float. atmospheric air rushes through said opening and moves the intermediate valve member to its lower position to close said port, thereby raising the pressure in said secondary chamber.

3. A centrifugal pump as claimed in claim 1, in which said second valve means controlling said return passaid manually-operable valve means is operable to isolate said vacuum source for the purpose of testing the source.

7. A centrifugal pump as claimed in claim 5, in which said manually-operable valve means is spring-urged to a closed position. and said spring is adjustable to control the liquid flow through the pump.

8. A centrifugal pump as claimed in claim 81 wherein said second valve means is operable to close said return passageway when the pressure in said primary chamber and the pressure in said secondary chamber are substantially equal. 

1. A centrifugal liquid pump of the type wherein an auxiliary vacuum source assists in priming and removing unwanted gas during operation thereof, the centrifugal pump comprising a primary chamber which contains liquid and receives unwanted gas which has entered the pump; an upper port in said primary chamber in communication with said vacuum source for removal of gas from said primary chamber; float-operated valve means which control said upper port; means defining a secondary chamber having upper and lower parts, said upper part being disposed between and in communication with said port and said vacuum source; a return passageway extending from said lower part of the secondary chamber to said primary chamber; second valve means in said return passageway operable to permit liquid flow from said secondary chamber to said primary chamber when the pressure in said secondary chamber is greater than that in said primary chamber; said secondary chamber having an upper opening in communication with said vacuum source and through which gas from said primary chamber is extracted via said port and the secondary chamber; said float-operated valve means being operable to open said secondary chamber to atmosphere when said port is closed by said float-operated valve means in response to a predetermined rise in the liquid level in said primary chamber; whereby entrained liquid deposited in said secondary chamber is discharged to said primary chamber through said return passageway as a result of the pressure differential which occurs between the primary and secondary chambers when said secondary chamber is opened to atmosphere.
 2. A centrifugal pump as claimed in claim 1, in which said float-operated valve means comprise an upright stem which extends through said port and is raised and lowered by said float; a lower closure member secured to said stem to seat on said port when the stem is in a raised position; an upper closure member which is secured to said stem and which controls an opening in the pump housing which connects said secondary chamber to atmosphere; an intermediate valve member which slides on said stem and which closes said port when in a lower position; whereby when the stem with the upper closure member is raised by the float, atmospheric air rushes through said opening and moves the intermediate valve member to its lower position to close said port, thereby raising the pressure in said secondary chamber.
 3. A centrifugal pump as claimed in claim 1, in which said second valve means controlling said return passageway has an outlet opening and said return passageway comprises a ball which seats on said outlet opening.
 4. A centrifugal pump as claimed in claim 1, further comprising third valve means controlling said upper opening in the secondary chamber against entry of liquid.
 5. A centrifugal pump as claimed in claim 1, further comprising manually-operable valve means for admitting atmospheric air to said secondary chamber to effect discharge of deposited liquid to said primary chamber.
 6. A centrifugal pump as claimed in claim 5, in which said manually-operable valve means is operable to isolate said vacuum source for the purpose of testing the source.
 7. A centrifugal pump as claimed in claim 5, in which said manually-operable valve means is spring-urged to a closed position, and said spring is adjustAble to control the liquid flow through the pump.
 8. A centrifugal pump as claimed in claim 1 wherein said second valve means is operable to close said return passageway when the pressure in said primary chamber and the pressure in said secondary chamber are substantially equal. 